Rett Syndrome (RTT) is a neurodevelopmental disorder caused by mutations in the Methyl CpG binding protein 2 (MECP2) gene. Deficient K+-Cl-co-transporter 2 (KCC2) expression is suggested to play a key role in the neurodevelopmental delay in RTT patients' neuronal networks. KCC2 is a major player in neuronal maturation by supporting the GABAergic switch, through the regulation of neuronal chlorine homeostasis. Previous studies suggest that MeCP2 mutations lead to changed KCC2 expression levels, thereby causing a disturbance in excitation/inhibition (E/I) balance. To investigate this, we performed protein and RNA expression analysis on post mortem brain tissue from RTT patients and healthy controls. We showed that KCC2 expression, in particular the KCC2a isoform, is relatively decreased in RTT patients. The expression of Na+-K+-Cl- co-transporter 1 (NKCC1), responsible for the inward transport of chlorine, is not affected, leading to a reduced KCC2/NKCC1 ratio in RTT brains. Our report confirms KCC2 expression alterations in RTT patients in human brain tissue, which is in line with other studies, suggesting affected E/I balance could underlie neurodevelopmental defects in RTT patients.

中文翻译：

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Rett综合征患者的死后脑组织中KCC2表达水平降低。

Rett综合征（RTT）是由甲基CpG结合蛋白2（MECP2）基因突变引起的神经发育障碍。提示K + -Cl-共转运蛋白2（KCC2）表达不足在RTT患者神经元网络的神经发育延迟中起关键作用。KCC2是神经元成熟的主要参与者，通过调节神经元氯的体内稳态来支持GABA能开关。先前的研究表明MeCP2突变导致KCC2表达水平改变，从而引起激发/抑制（E / I）平衡的紊乱。为了对此进行调查，我们对RTT患者和健康对照的死后脑组织进行了蛋白质和RNA表达分析。我们显示，在RTT患者中KCC2表达，尤其是KCC2a亚型相对降低。Na + -K + -Cl-辅助转运蛋白1（NKCC1）的表达不负责氯的向内运输，从而导致RTT大脑中KCC2 / NKCC1比率降低。我们的报告证实了人脑组织RTT患者中KCC2表达的改变，这与其他研究一致，表明受影响的E / I平衡可能是RTT患者神经发育缺陷的基础。